Spark-plug



A. DE CVLAIRMONT.

SPARK PLUG.

APPLICATION FILED SEPT. 13. 1919.

Patented June 14, 1921.

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ADOLFO DE CLAIRMONT, OF TOLEDO, OHIO, ASSIG-NOR TO THE CARBO-GASCOMPANY, OF TOLEDO, OHIO.

SPARK-PLUG.

Specification of Letters Patent.

Patented June 14, 1921.

Application filed. September 13, 1919. Serial No. 323,630.

T 0 all whom it may concern:

Be it known that I, AnoLro DE CLAIR- MONT, citizen of the United States,residing at Toledo, in the county of Lucas and State of Ohio, haveinvented certain new and useful Improvements in- Spark-Plugs, of whichthe following is a specification.

This invention relates to an improved spark plug for internal combustionengines and has as one of its principal objects to provide an eflicienttype of plug employing primary and secondary spark gaps to the end thata multiple spark will be had upon the passage of current through theplug.

The invention has as a further object to provide a plug of thischaracter which will in effect provide a compound plug so that shouldthe ground electrodes become short circuited a spark will still be givenoff between the main and intermediate electrodes of the plug.

A further object of the invention in this connection is to provide aplug wherein the intermediate electrode will be carried by a condenseremployed and wherein the condenser will be mounted directly upon theporcelain. insulator of the plug.

A still further object of the invention is to provide a plug which willnot leak compression.

And the invention has as a still further object to provide a plugemploying a cap for sealing a portion of the insulator so as to preventleakage around the insulator and wherein said cap will also serve as aprotectonfor the upper portion of the insulator.

Other and incidental objects will appear hereinafter.

In the drawings:

Figure 1 is a side elevation of my improved spark plug,

Fig. 2 is a vertical sectional view taken centrally through the device,

Fig. 3 is a detail perspective view of the porcelain insulator andintermediate electrode employed, these parts being shown disassembled,and

Fig. 4 is a detail perspective View of a slightly modified form of mainelectrode.

In carrying the invention into effect, I employ a metal shell 10threaded at its lower end portion for engagement in the spark plugorifice of an engine cylinder and provided at its upper end with theusual wrench receiving enlargement. Internally the shell is formed withan annular shoulder upon which is seated an appropriate gasket 11 andresting upon this gasket is the main insulator 12 of the plug, enlargedintermediate of'its ends to snugly fit within the shell while the lowerend portion of the insulator is reduced and terminates adjacent thelower en'd of the shell. The insulator may be formed of porcelain orother approved material. Surrounding the insulator above the.enlargement thereon is a gasket 13 similar to the gasket 11 andthreaded into the upper end portion of the shell to coact with theformer gasket is a nut 14 provided at its upper end with a wrenchreceiving flange. The insulator will thus be removably held upon theshell.

The insulator 12 carries a main electrode 15 extending axially throughthe insulator and cemented or otherwise secured thereto. At its lowerend portion the main electrode projects somewhat below the lower end ofthe insulator while at its upper end portion the electrode is extendedto project considerably above the insulator. Mounted upon the lower endportion of the insulator is a condenser 16. This condenser is in thenature of a metal ferrule which is snugly fitted around the lower endportion of the insulator to be suitably secured thereto, the condenserlying wholly "within the lower end portion of the shell and confrontingthe inner wall thereof in spaced parallel relation. Depending from thecondenser are oppositely disposed intermediate electrodes 17. As will beobserved, these intermediate electrodes are arranged to confront thelower end of the main electrode and extending downwardly and inwardlyfrom the lower edge of the shell to cooperate with the intermediateelectrodes are ground elec trodes 18.

Seated upon the upper 'end of the nut 14 around the insulator 12 is agasket 19 and snugly fitting over the upper end portion of the insulatorto seat against this gasket is a sealing cap 20 for the insulator. Thiscap may also be formed of porcelain or other suitable insulatingmaterial and freely receives the main electrode 15 therethrough. Uponthe upper end of the cap is arranged a gasket 21 similar to the gasket19 and threaded upon the main electrode to seat against the former rgasket is a nut 22 adjustable for tightly 1 the plug practically-leakproof at this point.

I clamping the cap over the upperend portion of the insulator andforming a sealed joint between the cap and nut 14 at the gasket 19 asWell as'a sealed 'oint between the nut and Furthermore; particularattention is directed to the fact that the cap will serve as a protectorfor the upper end-portion ofthe usual manner. for [connecting aconductor V construction, a spark will be formed between.

insulator. As is well known, spark plug in sulators are very oftencracked or brokenofi by'a blow from a wrench or other 'tool when thetool happens to slip during-the operation of removing a plug.- cap 20,would, in the present instance, re-

;ceive such a blow and under normal circumstances will prevent breakingof the insulator. Should the cap itself become broken, it

maybe readily replaced andat lessexpense than would be involved inrenewing the insulator with the parts permanently attached thereto.Threaded upon the upper end portion of the main electrode to confrontthe nut 22 is a thumb nut 23 which may, as suggested in the drawings, beemployed in the with the main electrode.

As will now be readilyunderstood in View ofthe previous description,when a circuitis closed. to the plug, current will flow throughthe mainelectrode 15 and will then jump to the intermediate electrodes 17 ofthecondenser l6, thus providing a spark at each of the gaps between themain electrode and the intermediate electrodes. 1 From the intermediateelectrodes the current will, of course,

coincidently jump to the ground electrodes 18 so that a spark will alsobe formed at each of the gaps between the intermediate and the groundelectrodes. I accordingly provide'a plug which, under normal conditions,will produce. a multiple spark and will accordingly insure properignition. In this connection, particular attention is directed tothe'fact that when the current jumps from the main electrode 15 to theintermediate electrodes 17, current will flow into the y condenser 16;tobe storedthereih. As will As will be seen, the

Learner quently, under ordinary conditions, be constantly charged forthus insuring the gen eration of what is generally termed a hot sparkbetween the intermediateand ground electrodes when additional current issupplied to the condenser from the; main electrode 15. Further, it is tobe noted in connection with this condenser that I provide a plug whichis, in efi'ect, a compound plug.

be appreciated, the condenser will conse- Uponthe formation of a shortcircuit between the main electrode and the condenser between theintermediate electrodes and the ground electrodes, a spark will,nevertheless, be produced at each of the gaps between the main electrodeand the intermediate electrodes. I accordingly provide a plug which willbe particularly free from the common fault of short circuiting.

In Fig. 4 I have illustrated aslightly modified form fmain electrode. Inthis figure the main electrode is indicated at 24 and this electrode is,at itslower end, formed with oppositely directed sparking points 25. As

will be seen, when this electrode is employed in lieu of the electrode15 of the preferred each of the sparking points 25 and the intermediateelectrodes of the condenser.

Having thus described the invention, what g is claimed as new is:

' In a spark plug, the combination-of a shell having a ground electrodedepending from the lower end thereof, an insulator fitting through theshell, a mainelectrode car- 'ried by the insulator, and a metallic bandsnugly fitting around the lower end portion of the insulator whollywithin the-lines. of the shell and next to the inner wall thereof inspaced relation to said wall to define an intermediate air gap betweenthe band and the shell throughout the length of the band,

there being an intermediate electrode depending from said band tocoiiperate with the main and ground elcctrodesbelow the lower end of theshell.

Intestimony whereof I afix my signature. ADOLFO de tILAlRtVlON'I; llil.W. [n 8.]

